Multiple fault segments ruptured during the 2014 Yutian earthquake, but the detailed source parameters and the mechanism of rupture complexity remain poorly understood. Here, we use high-resolution TanDEM-X satellite data and Satellite Pour l'Observation de la Terre-6/7 images to map the coseismic ground deformation field of the event. We find that the majority of coseismic slip occurred in the upper 10 km with the maximum left-lateral fault slip of ∼ 2:5 m at ∼ 6 km depth. The fault ruptured across a large 4.5 km extensional stepover from one left-lateral fault segment to another, with some right-lateral relay faulting in between. We find that the earthquake was followed by shallow afterslip concentrating at the southwestern end of coseismic rupture, in an area of many aftershocks and positive Coulomb failure stress change. Our findings demonstrate the power of satellite remote sensing technology in constraining source geometry and slip model of complex earthquakes when ground measurements are limited.
Bibliographical noteKAUST Repository Item: Exported on 2020-12-14
Acknowledged KAUST grant number(s): BAS/1/1353-01-01
Acknowledgements: The authors thank Y. Aoki and L. Bie for their helpful reviews. Satellite Pour l'Observation de la Terre (SPOT)-6/7 image correlation processing was performed by A. Truffier supported by Terre Solide, Océan, Surfaces Continentales et Atmosphère (TOSCA) Centre national d'études spatiales (CNES) program at Institute de Physique du Globe de Paris (IPGP). The research was supported by the National Natural Science Foundation of China (Numbers 41804015 and 41474013); the National Key R&D Program of China (2019YFC1509205); public funds received in the framework of GEOSUD, a project (ANR-10-EQPX-20) of the program “Investissements d'Avenir” managed by the French National Research Agency; and King Abdullah University of Science and Technology (KAUST), Grant Number BAS/1/1353-01-01.